Damn it, I will be back................


P.S. The thread I am ripping off.


https://www.evolutionm.net/forums/sh...&highlight=FPR

Al also tested teh Base FP witha pump at idle 52PSI, not good.

 

We're not arguing the A/F plots, we're arguing as to why.

Think about this...

The pump is stock on a car that delivers about 230whp on this dyno, and stock boost levels. When mods are made and the boost pressure is increased (as per the car in the dyno charts), this demands that the pump supply 70whp more of fuel AND more pressure because of the increased boost. If there is any weakness in the factory pump, it will be exposed right here, and it is. Just look at the factory A/F between 5-7k rpm and you an see the curve going leaner. This is almost certainly not intended.

The difference in A/F between the two pumps at 3.5-4k rpm is minor, ranging from ~11.8-12.4. Otherwise, the A/F lines are just jumbled together until it becomes apparent that the larger pump DOES in fact keep up with the increased flow AND pressure demands, upon which the lines diverge.

 

The stock pump flows 190LPH and is perfectly Adequate for the 16G in all levels on Pump gas. Iw as a dsm guy before this and it is well know that using a 195LPH pump is all that is needed for 16G cars ort else you over run the FPR and lose proper fuel control.


He is another Before and after Dyno with a pump added. NOTICE that the stock Fuel pump is holding a perfect 11-1 Ratio with 300WHP, hmmmmmmm, also notice what happnes with and upgraded pump. With a STATIC fule injector pulse, the only way to DUMP THAT MUCH FUEL, is to bump the FPR.

I say that the stock pump is no where near being over run, Buschur confirms this as well.



You may not agree with this but must admit it is 100% possible.

 

Another Interesting Read... Link here

https://www.evolutionm.net/forums/sh...sure+Regulator

 

The last dyno chart seems to prove what I was saying. Although the stock fuel pump may be able to supply 11:1 at high RPM, that doesn't mean it can continue raising fuel pressure 1:1 with boost pressure at high RPM. In the middle and lower RPM ranges fuel pressure must be the same with both pumps. The only way the A/F ratios would get richer like that is if the Walbro causes fuel pressure to raise at 1.5:1 over 5000 RPM or the stock fuel pump does not maintain 1:1 over 5000 RPM. I think the latter is more likely.

Paul

 

But if the injector pulse time is increased, the A/F will remain constant even with decreasing pressure. So you see, without a proper FP log, it's only guesswork and one can argue both ways until he's blue in the face.

It doesn't change the fact that is obvious regardless, which is a retune is necessary upon adding the upgraded pump. So long as that is done, it's a non-issue.

 

It is a variable voltage system, so cruisng the Fuel pump gets less juice and does less work. BUT at WOT, it gets full Juice.

guys, it is a 195LPH fuel pump, it is MORE THEN ENOUGH to fill at 300WHP, more then enough. Any DSM guys here? I mean it is a non-issue.

Again I believe the Fuel Pressure is bumped across the board. David Bushur has tested the STock pump, holds fine at 350WHP properly tuned. 400WHP? No, it won't do that, 300WHOP is a JOKE and easilly achieved with this pump. DSM guys Upgrade to a pump this size when they plan on ONLY a 16G. 20G's and so need a 255LPH.

 

I understand that it's a variable voltage system. I was under the assumption that it would go to the higher voltage setting before 5000 RPM under WOT. I could be wrong on that. Knowing when the voltage changes would help with the analysis of the dyno sheets. If they voltage does change at 5000 RPM, then that would explain the fuel enrichment over 5000 RPM, but if it changes before that, then I'm still of the opinion that fuel pressure drops at high boost levels over 5000 RPM with the stock fuel pump.

-Paul

 

You called. LOL
I hope this helps a little.
The stock fuel pump (a 160) is not a weakness for 350 whp. This is why;
http://www.roadraceengineering.com/f...pflowrates.htm
The stock pump at the higher volltage out flows a 190 at 12v., which is well know to support over 350whp.
Here's a diagram of the wiring;
http://www.roadraceengineering.com/e...elpumpinfo.htm
Someone just needs to monitor load vs. voltage at the fuel pump to see when it kicks over. Not RPM.
If your worried about fuel pressure with a 255, make sure you buy the right one. There's two; a 255lph and a 255lph high pressure unit.

 

Thanks for the link Larry.

Let's have a closer look at this...

The flow capacity of the stock EVO pump in RRE's page is ~158lph at 15psi of boost at the 14V setting. At 30psi of boost, the flow rate is down to ~113lph. Mathematical interpolation shows it to be around 143lph at 20psi.

Gasoline has a specific gravity of ~737kg/m3, and there are 1000L in a cubic meter. This equates to 737/1000 = 737g/L, which equals 1.62lbs/L given 454g/lb.

Given this and a BSFC of 0.55lbs/hr/hp, we use the 143lph figure to get 231lbs/hr, which equates to a theoretical max of 420bhp at 20psi of boost.

If we insert the 255lph unit, we get a theoretical max capacity of somewhere around 645bhp at 30psi of boost.

Just FYI.

 

Just curious where you got your BSFC value?

-Paul

 

The BSFC for a modern multivalve, port injected, normally aspirated engine hovers around 0.45. A turbo engine as it comes from the factory typically hovers around 0.6-0.65, depending on the factory tuning. I estimate a retuned (aftermarket) turbo car (i.e. tuned such not as to run pig rich up top) to be in the neighborhood of 0.55.

 

Both actually over run it


At any rate I got a New FPR today and it goes on the car tomorrow along with a Dyno run

 

OOOPS!

I don't get what you are saying.

Is it 52 at idle with the vacuum hose connected? Or 52 with no hose connected?

No vacuum source or 0 boost the fuel pressure is spec'd at 42-45 or commonly known 43.5,
When vacuum source is present at idle the pressure is 33.
Remember cams for one will raise the pressure because there is less vacuum.

The pressure should rise in direct relationship to boost pressure. If not then the pump is overrunning the FPR at I'd be a little suprised.

 

52 no matter what

It is over run, meaning it is stuck at 52 PSI but it CAN increase, can't go below 52 though. so anything 10PSI of boost and under you have a static fuelpressure of 52PSI